Radiation torch having an electrode for supplying and exhausting gas



w E- 2 f n bflUbD KETUKEWUE btfiiwil KUU 6, 1968 J. E. ANDERSON 3,364,3

RADIATION TORCH HAVING AN ELECTRODE 1 FOR SUPPLYING AND EXHAUSTING GAS Filed June 7, 1965 2 Sheets-Sheet 1 POWER SUPPL V C J I?! "o ARGON PLUS RARE 0 Z EARTH SPECTRUM7 d ARGON SPECTRUM o:

WAVELENGTH (ix) I M oHN' fiWE RsoN ATTORNEY Jan. 16, 1968 J. E. ANDERSON 3,364,387 RADIATION TORCH HAVING AN ELECTRODE FOR SUPPLYING AND EXHAUSTING GAS Filed June '7, 1965 2 Sheets-Sheet 2 ABSOLUTE INTENSITY (WATTS/CMZ/IOOA) J 2600 4000 6000 8000 IQOOO |2,000

INVENTOR ,A/ WAVELENGTH (3) JOHN E. ANDERSON 064 9 5 MHMX United States Patent 3,364,387 RADIATION TORCH HAVING AN ELECTRODE FOR SUPPLYING AND EXHAUSTING GAS John E. Anderson, Indianapolis, Ind., assignor to Union Carbide Corporation, a corporation of New York Filed June 7, 1965, Ser. No. 461,775 4 Claims. (Cl. 315-111) This invention relates to heat and light radiation sources, and more particularly, to a torch for such purpose.

According to the invention, novel apparatus is provided for producing an elongated source of heat and light. Such apparatus comprises, in general, a tube of transparent material, such as quartz, providing an arc chamber; arc terminal electrodes positioned within such chamber in substantially concentric relation with the longitudinal axis of said chamber; one of said electrodes having a central gas exit passage in line with such axis; and inlet gas passage means for directing gas in a swirling path along the inner surface of said tube; said inlet passage means being located in proximity to the electrode having the central gas exit passage.

A critical feature of this invention lies in the arrangement whereby the gas is injected into the arc chamber in a swirling fashion from the end of the tube where the electrode having the central exit passage is located. With this arrangement, the swirling gas flows along the inner face of the tube forming the arc chamber toward the opposite end of the tube from whence the flow reverses itself and flows toward and out the central exit passage in a region of the central axis of the arc chamber. This flow pattern results in a low pressure region at the axis of the arc chamber where the arc is maintained.

' The phenomenon creating the low pressure region can be likened to a tornado. In each case, there is a mass of rotating gas surrounding a central column of even more rapidly rotating gas. As each element of gas spirals inward along a path of decreasing radius, its tangential velocity increases in accord with the natural tendency for momentum to be preserved, its centrifugal force increases accordingly, and the pressure gradient opposing this force causes the pressure to be lowest at the center. The overall effect of this tornado phenomenon is the creation of an aerodynamic nozzle which restricts the cross sectional area of the arc and increases are stability.

Because of this phenomenon, the present invention achieves a long, extremely stable, high intensity are. Indeed, arcs 4 to inches in length have been achieved with current densities of 1000 amp/cm? or greater at substantial arc chamber pressures. Thus, there is a marked difference in the performance of the are when the gas is injected at the end of the chamber opposite the electrode having the central exit passage, or when the gas is injected from both ends of the chamber with a single gas exit passage.

The invention also contemplates the use of rare earths to increase the intensity of the are as a light source. The rare earths can be injected into the system in the form of powder, or as is preferable, they may be injected in rod form. When being injected in rod form, the rod itself acts as the electrode opposite the electrode having the central gas exit passage.

In the drawings:

FIGURE 1 is a fragmentary view mainly in longitudinal vertical section of apparatus illustrative of the invention;

FIGURE 2 is an enlarged cross sectional view of the torch taken on line 2-2 of FIGURE 1;

' FIGURE 3 is a graph of typical wave length/intensity conditions of operation of the torch with argon gas; and

3,364,387 Patented Jan. re, 1968 ice FIGURE 4 is characteristic spectrum showing the effect of rare earth injection into the argon gas are.

As shown in FIGURES 1 and 2, the illustrated apparatus generally comprises a torch T provided with an electrode 10 which is in axial alignment with a substantially flat ended nozzle electrode 12 and separated therefrom by a gas tight chamber 14. Electrode 10 is held by a suitable holder 16 providing a substantially flat annular surface facing the chamber 14. Both electrodes can be cooled through water cooling, for example. Electrode 10 is preferably constructed from an emissive material such as tungsten, or tungsten containing thoria, or as another alternative the insert electrode of copending ap plication Ser. No. 183,880 can be used. Nozzle electrode 12 is constructed of a good thermally conductive material, such as copper.

An are 18 is established and maintained by connecting power supply 20 to the electrodes. Direct current with straight or reverse polarity, as well as alternating current can be used. The are is initiated by any suitable means, such as high frequency starting, for example. Chamber 14 is constructed of a shell such as tube 22, at least a portion of which is transparent. Quartz, for, example, may be used.

A long narrow intense are 18 that is extremely stable is achieved through the use of a novel form of swirl gas flow. The mode of operation, according to the invention, it is to inject the gas so that it swirls about the inner face of tube 22 as it travels from one end of the chamber 14 to the other. Upon reaching the end opposite its entrance the flow, still swirling, reverses its direction and travels in close proximity to the arc.

Thus, as shown in the drawings, the arc gas enters through inlet 24 into annulus 26 from whence it asses through a plurality of tangentially directed apertures orports 28 so as to impart a swirling motion to the gas as it proceeds toward the opposite end of the chamber 14 along the inner face of the tube 22. Upon reaching the opposite end, the direction of gas flow reverses, and the gas travels back toward the nozzle end in close proximity to the are 18, still in the swirling vortex fashion. The gas then exits through passage 30 in the nozzle electrode 12. This gas flow pattern operates so as to function inlthe same manner as a tornado to create a low pressure region at the axial center of the chamber where the are 18 is running.

Not only does this novel mode of flow result in an are 18 that is highly dense, and stable at lengths much greater than one inch, but it very effectively protects the transparent tube 22 from the heat effects of the arc.- This concept makes possible the production and maintenance of an are having a density of at least 1000 ampJcm. without deterioration of the transparent shell 22. a

In the practice of the invention, any inert gases selected from the class consisting of argon, xenon and krypton can be used.

FIGURE 3 shows typical torch operating conditions and the resulting intensities achieved at various wave lengths with argon gas. In acquiring the data, a torch T of general type depicted in FIGURE 1 was used. However, a tungsten button electrode was used in place of stick electrode 10.

As previously stated, the present invention also contemplates the use of rare earths in order to increase the brightness of the are so as to render the apparatus particularly useful as a light source. According to the invention this is preferably done by substituting a rare earth rod for the stick electrode 10. The rare earth rod would thus be acting as a consumable electrode. As the rod erodes away, the rare earth enters the arc to effectively increase the arcs brightness.

FIGURE 4 shows the effect of rare earth injection into an arc, wherein argon gas was fed to the chamber of FIG. 1. The rare earth was fed in the form of a consumable electrode, replacing the stick electrode 10.

What is claimed is:

1. A radiation torch comprising in combination a quartz shell of substantially tubular shape, means providing arc electrodes adjacent the ends of said shell, one of said electrodes being located and shaped so as to maintain the corresponding end of the arc in the axial center of the chamber afforded by said shell, means supporting said are centering electrode providing a substantially flat annular surface facing such chamber the other electrode spaced at least 1 inch from said are centering electrode and being in the form of a nozzle having a central gas exit passage, said nozzle having a substantially flat ended portion projecting into such chamber in axially spaced relation to the inner surface of said shell, and also having an annular gas passage in communication with a plurality of tangentially arranged ports, representing the sole means, for discharging gas into such chamber means for supplying gas to such ports so that such gas follows a tornado like pattern with a swirling path along such surface, flowing first toward said are centering electrode, where the flow of gas reverses itself and flows toward and out of such central gas exit passage in said nozzle, resulting in a relatively low pressure region adjacent the longitudinal axis of such chamber, and means for energizing an arc in such region between said electrodes.

2. A torch as called for by claim 1 in which said are centering electrode is in the form of a pointed stick.

3. A radiation torch comprising; an elongated tubular envelope providing an arc chamber having transparent portion; means providing arc electrodes located adjacent the ends of such chamber and being spaced at least one inch apart, one of said electrodes being in the shape of a nozzle having a central gas exist passage; means for energizing an electric arc in the chamber between said electrodes, and means including a plurality of tangentially arranged inlet ports located only at said nozzle electrode end of the chamber for introducing arc gas through said chamber in the form of a tornado which sweeps as an outer stream from the nozzle electrode end of said chamber to the other end of said chamber along substantially the full length of the inner surface of said envelope and then reverses itself, flowing back as an inner stream within such outer stream to said central gas exit passage, concentrating said are adjacent the axial center of said chamber for substantially the entire length of the chamber.

4. A torch as defined by claim 3 in which said nozzle is surrounded by a substantially flat annular surface facing such chamber and wherein said gas inlet ports are located in the rim of said nozzle.

References Cited UNITED STATES PATENTS 3,075,065 1/1963 Ducati 313231 X 3,153,169 10/1964 Bauer 313--228 X 3,222,568 12/1965 Richards 315111 3,255,379 6/ 1966 Miller 313231 X 3,292,028 12/1966 Van Ornum 313-231 S. D. SCHLOSSER, Primary Examiner.

JAMES W. LAWRENCE, Examiner. 

1. A RADIATION TORCH COMPRISING IN COMBINATION A QUARTZ SHELL OF SUBSTANTIALLY TUBULAR SHAPE, MEANS PROVIDING ARC ELECTRODES ADJACENT THE ENDS OF SAID SHELL, ONE OF SAID ELECTRODES BEING LOCATED AND SHAPED SO AS TO MAINTAIN THE CORRESPONDING END OF THE ARC IN THE AXIAL CENTER OF THE CHAMBER AFFORDED BY SAID SHELL, MEANS SUPPORTING SAID ARC CENTERING ELECTRODE PROVIDING A SUBSTANTIALLY FLAT ANNULAR SURFACE FACING SUCH CHAMBER THE OTHER ELECTRODE SPACED AT LEAST 1 INCH FROM SAID ARC CENTERING ELECTRODE AND BEING IN THE FORM OF A NOZZLE HAVING A CENTRAL GAS EXIT PASSAGE, SAID NOZZLE HAVING A SUBSTANTIALLY FLAT ENDED PORTION PROJECTING INTO SUCH CHAMBER IN AXIALLY SPACED RELATION TO THE INNER SURFACE OF SAID SHELL, AND ALSO HAVING AN ANNULAR GAS PASSAGE IN COMMUNICATION WITH A PLURALITY OF TANGENTIALLY ARRANGED PORTS REPRESENTING THE SOLE MEANS, FOR DISCHARGING GAS INTO SUCH CHAMBER MEANS FOR SUPPLYING GAS TO SUCH PORTS SO THAT SUCH GAS FOLLOWS A TORNADO LIKE PATTERN WITH A SWIRLING PATH ALONG SUCH SURFACE, FLOWING FIRST TOWARD SAID ARC CENTERING ELECTRODE, WHERE THE FLOW OF GAS REVERSES ITSELF AND FLOWS TOWARD AND OUT OF SUCH CENTRAL GAS EXIT PASSAGE IN SAID NOZZLE, RESULTING IN A RELATIVELY LOW PRESSURE REGION ADJACENT THE LONGITUDINAL AXIS OF SUCH CHAMBER, AND MEANS FOR ENERGIZING AN ARC IN SUCH REGION BETWEEN SAID ELECTRODES. 